Contains an image of a 32-bit or 64-bit process at the time of an error, in the AIX 4.3 file format.
A core file is created in the current directory when various errors occur. Errors such as memory-address violations, illegal instructions, bus errors, and user-generated quit signals commonly cause this core dump. The core file that is created contains a memory image of the terminated process. A process with a saved user ID that differs from the real user ID does not produce a memory image. The contents of a core dump are organized sequentially in the core file as follows:
|Core header||Defines basic information about the core dump, and contains offsets that locate the remainder of the core dump information.|
|ldinfo structures||Defines loader information.|
|thrdctx structures||Defines kernel thread state information. Since the faulting thread thrdctx structure is directly saved in the core header, additional structures are saved here only for multi-threaded programs.|
|segregion structures||Contains the address, size, and type for shared memory segments of the faulting process.|
|Default user stack||Contains a copy of the user stack at the time of the core dump.|
|Default data area||(Optional) Contains the user data section.|
|vm_infox structures||(Optional) Contains offset and size information for memory mapped regions.|
|Memory mapped regions||(Optional) Contains the memory mapped regions.|
The core_dumpx structure, defined by the core.h file, occurs at the beginning of a core file. The core_dumpx structure includes the following fields:
|Field Type||Field Name||Description|
|char||c_signo||The number of the signal that caused the error|
|char||c_flag||A bit field that describes the core dump type. The meanings of the bits are as follows:|
|FULL_CORE||core contains the data sections (0x01)|
|CORE_VERSION_1||core was generated by version 4 or higher of the operating system (0x02)|
|MSTS_VALID||core contains mstsave structures (0x04)|
|CORE_BIGDATA||core contains big data (0x08)|
|UBLOCK_VALID||core contains the u_block structure (0x10)|
|USTACK_VALID||core contains the user stack (0x20)|
|LE_VALID||core contains at least one module (0x40)|
|CORE_TRUNC||core was truncated (0x80)|
|ushort||c_entries||The number of core dump modules|
|int||c_version||Core file format version|
|unsigned long long||c_fdsinfox||Offset to fd region in file|
|unsigned long long||c_loader||Offset to loader region in file|
|unsigned long long||c_lsize||Size of the loader region|
|uint||c_n_thr||Number of elements in thread table|
|unsigned long long||c_thr||Offset to thread context table|
|unsigned long long||c_segs||Number of elements in segregion|
|unsigned long long||c_segregion||Offset to start of segregion table|
|unsigned long long||c_stack||Offset of user stack in file|
|unsigned long long||c_stackorg||Base address of user stack region|
|unsigned long long||c_size||Size of user stack region|
|unsigned long long||c_data||Offset to user data region|
|unsigned long long||c_dataorg||Base address of user data region|
|unsigned long long||c_datasize||Size of user data region|
|unsigned long long||c_sdorg||Base address of privately loaded region|
|unsigned long long||c_sdsize||Size of user privately loaded region|
|unsigned long long||c_vmregions||Number of anonymously mapped areas|
|unsigned long long||c_vmm||Offset of start of vm_infox table|
|struct thrdctx||c_flt||Faulting thread's context and thread data|
|struct userx||c_u||Representation of the user struct and process data|
The c_flt field in the core dump contains the thrdctx structure of the faulting thread. The thrdctx structure includes the thread data and registers as they existed at the time of the fault. The format of the thread context structure is defined by thrdctx structure (in the core.h header file) as follows:
|thread data (in procinfo.h header file)|
state of registers if 64-bit process, or
state of registers if 32-bit process
The c_u field follows this information in the core dump. The c_u field contains the userx structure including the user structure fields, and the process data as they existed at the time of the fault. The format of the process information structure is defined by the userx structure (in the core.h header file) as follows:
|userx||procsinfo64||process data (in procinfo.h header file)|
The ld_info structure and then the thrdctx structures of the other threads (if the process is multi-threaded) follow in the core dump.
The segregion structure and then the user-mode stack follow in the core dump.
The segregion structure contains the information about a shared memory region of the faulting process.
|segment start address|
size of the segment
type of the document
The first three fields of the core_dumpx header in AIX 4.3 are the same as that of the core_dump header in AIX 4.2. However, the c_entries are always zero on AIX 4.3 systems to distinguish them from the AIX 4.2 core file formats. Further, the pi_flags2 field of the procsinfo64 structure determines if the core file is of a 32-bit process or a 64-bit process.
The AIX 4.3 system can be forced to create core files in an AIX 4.2 core file format via the SMIT tool. However, this enforcement is valid only for 32-bit processes.
By default, the user data, anonymously mapped regions, and vm_infox structures are not included in a core dump. This partial core dump includes the current thread stack, the thread thrdctx structures, the user structure, and the state of the registers at the time of the fault. A partial core dump contains sufficient information for a stack traceback. The size of a core dump can also be limited by the setrlimit or setrlimit64 subroutine.
To enable a full core dump, set the SA_FULLDUMP flag in the sigaction subroutine for the signal that is to generate a full core dump. If this flag is set when the core is dumped, the user data section, vm_infox, and anonymously mapped region structures are included in the core dump.
The param.h file.
The adb command, dbx command.
The raise subroutine, setrlimit and setrlimit64 subroutines, setuid subroutine, sigaction subroutine.
The Header Files Overview in AIX Version 4.3 Files Reference defines header files, describes how they are used, and lists several header files for which information is provided in this documentation.